The M4 should have sufficient resources to run a light weight OS. I wouldn't consider anything with lots of drivers. Android or light weight Linux should work. I'd consider Free RTOS for non-dynamically loaded applications.
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.